Et tu, Economist

AMERICANS are getting fatter: obesity rates have risen 74% in the past 15 years to nearly 28% of the adult population. And they are driving more: the number of miles driven by each licensed driver (VMT/LD), excluding commercial vehicles, increased by an average of 0.6% a year between 1988 and 2008. Academics at the University of Illinois have found a striking correlation between these two variables—but with a large time lag. They noted that previous research had found that changes in diet had an effect on body weight only after some six years. Therefore VMT/LD in 2004 is correlated with obesity in 2010… This near-perfect correlation (99.6%) permits predictions about obesity rates. Since VMT/LD fell in 2007 and 2008, America’s obesity rate could fall to as low as 24% in 2014…